Converting std R80 to off road (GS) spec

[BigyellowGS]

The R80 project has taken a massive step forward today..

After a "quick" trip up to see Rob I now have most of the large parts I need to get the conversion underway.

And this afternoon the R80 was again stripped down to just the main frame & engine.

A twin shock swing arm was then fitted complete with a 34/11 bevel box.. And a twin shock subframe offered up... everything went in without fuss and after a bit off fidding I've worked out the length of the shocks I'm going to need to get the ride height right (Should work out approx the same as a STD R80G/S).

Rear wheel has now been dumped into the boot of my car and will be delivered to a freind to be rebuilt with a 2.50 rim (checked the clearance to the arm and it should be fine)... At the same time he'll be rebuilding the front wheel from 19" to 21".

the front end I'm fitting is I guess from an early R100.. And will have just one ATE caliper. Again this went in without too much fuss.. Although my original R80 yokes really didn;t want to part company with the frame they have called home for the last 20 years!

This is purely a dry build at the moment.. I'll be photographing things as I go though the build proper.. So hopefully I'll be able to post a bit about the "ease" of this conversion... (god I'm an optomist at times).

Rob - Thanks again for the tea, the great deal on the parts and of course the chance to take some measurements from your 80g/s... Thats one stunning bike you have there!

 

[lurcher]

Dryfit

First dry fit of all the big bits

 

[(RIP) Proff]

Afternoon Lurcher, v v nice, is that mono lever extended ?? or are my eyes deceiving me ??

If so, how and details please

 

[Trippy]

Good to meet you Mark, fancy that two Airheads 50 yards apart and we didn't know it!
Sounds like your going to be a handy person to know
I'm on rest days next week so will come and have a good look mon or tue

 

[Trippy]

Afternoon Lurcher, v v nice, is that mono lever extended ?? or are my EARS deceiving me ??

If so, how and details please

....

 

[lurcher]

Thanks to trippy I can post Pics. Yep the s/a is 50mm loner machined block between b/box and s/a. I dont like the idea of lengthening the drive shaft by welding as it acts as a torsion spring so have extended the the drive socket instead.
I think the Mono frame gives a better angle for the shock to work at IE not so laid down. The forks are too long at the mo so will be shortened by about 2". Paralever rear wheel machined to fit mono b/box. large cast disc brembo 4 pot. Modified subframe er thats all I can think of at the mo.

 

[(RIP) Proff]

....

Bollox Trippy, he HASN'T extended the lever, he's spaced bevel housig block which was not obvious at first, I'm used to seeing ones like Wrefords

I like the Lurchers idea as it will be cheaper than the HPN alternative !!


Anyhooo I thought you were supposed to be working, so answer the phones and work yer radio and stop fecking SURFING !!!!!

 

[Kenny]

Looking good Lurcher...but please get Trippy to take the photos...we love projects on here

 

[lurcher]

It's an interesting point, have I extended the b/box or extended the s/a? Either way the lever ratio is extended. I cant take the credit for the idea, I saw it somewhere on the interweb. I had a 4" longer twinshock, post '81 s/a converted to single shock but that wouldnt work with the 2-1 exhaust. And I think the monolever looks better. It also gets rid of the spline mounting system for the wheels of the older bikes and the taper bearings in the hubs. Plus if you extend the s/a with this system you dont have to make a huge jig to make sure everything stays in line while welding.

 

[BigyellowGS]

Looking good Lurcher!

My R80 is progessing slowely... Although my dining room is now full of parts!

Front forks are fitted (awaiting top yoke).

Front wheel is with Jon @ Redshift motorcycles being rebuilt to 21".

I'll be picking the wheels up on friday.. all cleaned and shod in metzler enduro's.

I have the solo seat, front & rear mudguards, center stand, handlebars, ront caliper etc all sitting in my dining room..

the rear shocks have proved more difficult to source.. the Xl500 items i had were too long.. I need 365mm eye to eye... But a friends given me a pair of Z900 ones which are the right length.. I'll be interested to see if they are sprung about right..

So hopefully saturday will be the big day.. getting the old girl into her new suspenders and boots.. might even fire her up.. although with only the front pipes & collector box as I've still got to figure out the exhausts.

I'll post pics on sunday!

 

[lurcher]

Hi BYGS The popular choice years ago were Maico twin shocks. If you find the Z shocks fit and are nearly correct then you could get the equivalent Ikons with different springs . Falcon shocks are good but pricey but you can specify length, damping and spring rate. Hagons are a very helpful bunch and know what they are talking about and prices are reasonable.

 

[bustupbiker]

Hi BYGS The popular choice years ago were Maico twin shocks. If you find the Z shocks fit and are nearly correct then you could get the equivalent Ikons with different springs . Falcon shocks are good but pricey but you can specify length, damping and spring rate. Hagons are a very helpful bunch and know what they are talking about and prices are reasonable.

And who has a Maico sat a sittin in the back garden and no body wants it

 

[lurcher]

Twin shock enduros are classics and worth money in the off road racing world but otherwise wack the Maico front end on, extend the s/a and wack the maico shocks on, et voila an ISDT BMW

 

[Rob Farmer]

I've just come across these pictures on my hard drive. The bike was for sale on Ebay a few months back. Looks very well done. Early heavy flywheel gearbox but later timing case so single timing chain and bean can ignition. Anybody know what the forks are?

The pictures were taken from Ebay.

 

[BigyellowGS]

Now thats the sort of thing I'm hoping to end up with!

Strangely enough I've got exactly the same rear and front mudguards sitting in my workshop ready for my project!

Unfortunatly my friend Jon has not finished my front wheel rebuild yet.. But at least the rear is back nicely shod in its new Metzler Enduro 3

So tomorrow is going to be everything done apart from the front wheel! God I'm an optomist.. Or a sadist.. hmmm...

Cheers Rob.. the top yoke & frok tops arrived today! I'll owe you a few beers at some point!

 

[MattW]

I've just come across these pictures on my hard drive. The bike was for sale on Ebay a few months back. Looks very well done. Early heavy flywheel gearbox but later timing case so single timing chain and bean can ignition. Anybody know what the forks are?

Mmm - that's lurvely

 

[lurcher]

Nice tidy bike. I'll be happy if mine is half as good. Any ifo on how much longer the s/a is?

 

[BigyellowGS]

okay... after 5 hours in the workshop my project R80 is starting to look a little bit more like a bike again!

Just a few piccies to show what I have achieved today:

Just as a reminder this is what the bike looked like when I purchased it a few months ago:

Starting the strip down:

Twin shock arm & bevel box fitted:

And then the subframe followed by the Z900B rear shocks (370mm eye to eye about 4cm longer than the standard items)

Forks, yokes and new handlebars go in without fuss:

Mmmmmm... new bars.. (darned expensive new bars):

Rear mudgaurd and tail light unit goes in... (an ebay bargain at 12 quid)..

Just to get an idea of how she will look I bunged the tank & solo seat on (a bargain from motobins special offers section) and lined up the front guard:

rear view:

Riders view:

and front:

Shame my friend Jon @ redshift motorcycles hadn't finished the front wheel otherwise I might have got her rolling today! (great guy though.. 25 quid labour to strip the 19" rim off and build the wheel up with my new 21" rim)

Still got a whole list of things to sort out though:

longer throttle & clutch cables (new I'd forgotten to order something)
Front brake line fitting & bleeding
Mount the front guard properly
Sort out some kind of rack to go behind the solo seat.
Fit the new taller center stand (again a motobins special offer item).

Oh... and last but not least... figure out what I'm doing about the exhausts.. as the current collector box exits now point directly at the twin shock arm... hmmm.. Think I'll have a beer or three and mull that one over!

Cheers again for all the help and pictures to inspire!

 

[Rob Farmer]

Great stuff

How about inverting the exhaust pipes and rigging up a collector box?

I had the wheels and parts you have on your bike with the idea of building a copy of one of these:-

I'm glad you made good use of them

 

[Rob Farmer]

Nice tidy bike. I'll be happy if mine is half as good. Any ifo on how much longer the s/a is?

Turns out I copied the original Ebay advert as well:-

First registered as a R100RS in 1977. Modifications as follows, Husky 500 upside down forks re-valved and sprung to suit bike.
White power rear shocks.
Swingarm lengthend by approx four inches.
R80GS subframe modified and fitted together with GS seat.
Stainless downpipes and modified Harris silencers (Not too loud, just right!!). Lightened flywheel and gas flowed heads.

Bad points,
clutch slips under hard throttle.
Cylinder heads not converted for unleaded.

I built this bike about 15 years ago and have toured, ridden it off road on many occasions and even raced it at Silverstone!!. If my memory serves me well I won the MCC Lands end class award on it twice.

It is a go anywhere do anything on it bike. Not for the novice or faint hearted. If you do not know your bikes do not mess me about with silly questions. It also comes with pannier frames and Krauser panniers.